1. Field of the Invention
This invention relates generally to a chemical reaction vessel that can be used for the in situ preparation of flowable viscous products. The reaction vessel incorporates an internal piston that assists in the removal of reaction products from the interior of the vessel.
2. Related Technology
Chemical reactors or reaction vessels used in the production of viscous products often suffer from reduced yields because the reaction product cannot be completely removed from the reactor. An added complication in producing viscous products is the effort and expense in cleaning the reactor for re-use. In addition to reactor down-time, cleaning often produces large volumes of sometimes hazardous or difficult-to-dispose-of waste. Indeed, the volume of waste material from the cleaning operation may exceed the volume of the reactor itself.
The use of pistons or piston-like devices for discharging flowable viscous products from vessels used for the transport or storage of semisolid fluid materials is disclosed in several patents. For example, Watson U.S. Pat. No. 5,341,726 describes an elongated transport tank having a cylindrical piston with a radial, annular seal. The piston is sized so that its periphery bears against the walls of the transport tank to assist in the removal of viscous products. Other examples of the use of internal pistons to remove viscous materials from the interior of storage or transport tanks are depicted in U.S. Pat. Nos. 3,203,674, 3,828,988, 4,721,235, and 5,114,054.
Chemical reaction vessels, which are capable of operating at elevated temperatures and pressures and in the presence of solvents and/or corrosive chemicals, present a different environment from that of a storage or transport vessel.
U.S. Pat. No. 3,709,641 discloses an apparatus for preparing non-flowable gelatinous materials. The apparatus includes a closed reaction vessel that has a vertically-movable internal piston that is used to discharge non-flowable, semi-solid material onto an extrusion head. The apparatus is designed so that the piston fits loosely, i.e., the juncture of the piston with the reaction vessel is not fluid-tight. Because the apparatus would allow flowable materials to migrate around the periphery of the piston, the device depicted in U.S. Pat. No. 3,709,641 would not overcome the problem addressed by the invention.